Cut each onion into wedges. Wash the carrot, turnip, and leek and cut these into cubes.

In a frying pan, melt the butter. Sear the roast and bones on all sides. Remove the roast and bones, then add 1 cup broth to the frying pan, and with a wooden spoon, scrape off any bits that are stick to the bottom of the pan.

Put roast and bones in a large roasting pan and pour the pan juices over them. Add the vegetables to the roasting pan as well.

Bake the meat for 1 1/2 to 2 hours. Every 15-20 minutes, pour some of the dark beer over the meat to baste it and to get some liquid in the pan.

Remove the pan from the oven. Transfer the roast to a plate, cover to keep warm.

Pour the pan drippings and juices through a sieve into a sauce pot. Combine the flour and 3 tablespoons broth. Slowly drizzle this into the gravy, whisking so that no lumps form. Bring the gravy to a boil. Season with salt and pepper.

Cut the roast into 1/2 inch slices. Arrange the slices on a serving plate, and drizzle with a little gravy.